Pump-gear and piston combination with unloading



PUMP-GEAR AND PISTON COMBINATION WITH UNLOADING Filed April 17, 1948 J. A. LAUCK June 20, 1950 2 Sheets-Sheet 1 June 20, 1950 J. A. LAUCK 2,512,025

PUMP-GEAR AND PISTON COMBINATION wn'a UNLOADING Filed A rii 17, 1948 2 Sheets-Sheet 2 31-5 276 V Y'\ W Patented June 20, 1950 PUMP-GEAR AND PISTON COMBINATION WITH UNLOADING John A. Lauck, Shaker Heights, Ohio, assignor to Borg-Warner Corporation, Chicago, Ill., a corporation of Illinois Application April 17, 1948, Serial No. 21,623

5 Claims.

This invention relates to pressure loadable and unloadable pumps, of the character having axially displaceable bushings effective to seal and unseal the side faces of intermeshing gears; and particularly to an improved arrangement for economically and effectively assuring the positive action of the loading and the unloading pressure responsive control means.

This invention is an improvement over that disclosed and claimed in co-pending Lauck application, Serial No. 774,720, filed September 18, 1947, Patent No. 2,505,191, April 25, 1950 and is particularly directed to the novel form and mode of operation of the energizing pump in combination.

It is an object of this invention to provid in an assembly of the present character, a simplified and efiective auxiliary pressure generator capable of supplying the relatively small volume of pressure liquid necessary to compensate for leakage and maintain the pilot control valve positively in operated position following the opening thereof, thus avoiding any tendency on the part of the pressure loadable bushings to hunt.

A more specific object is the provision in combination with a gear pump of the present pressure loadable and unloadable character, of a relatively simple and inexpensive auxiliary single piston energizing pump of very small displacement of a value below that normally practicable of attainment with a gear pump, including forming one of the axially extending journals of the gear pump with a. reduced eccentrically disposed shaft and arranging the same to effect the requisite reciprocation of a small piston.

Other objects, advantages, and uses of the invention will become apparent upon reading the following specification taken in connection with the accompanying drawing forming a part thereof and wherein:

Fig. 1 is an axial cross-sectional view taken substantially on the line Il of Fig. 3 bringing out to advantage the novel arrangement of the energizing pump in combination with the main D p;

Fig. 2 is a cross-sectional view taken substantially on the line 2-2 of Fig. 1 bringing out to advantage the arrangement of pilot control valve and pressure relief valve;

Fig. 3 is a transverse cross-sectional view taken substantially on the line 33 of Fig. 1 further bringing out to advantage the novel relationship of the energizing pump in combination with the.

main pump; and

Fig. 4 is a schematic layout view partially in section bringing out to advantage the mode of operation.

Referring in greater detail to the figures of the drawing, a plural pump unit or pressure generator unit incorporating a preferred embodiment of the present invention is indicated generally at III as comprising a first primary intermeshing gear type pump or pressure generator P--! and a, second auxiliary or energizing pump or pressure generator P-2 in combination therewith.

Pump housing II is formed with an inlet l2 and an outlet l3, pump P--| being contained therein and comprising intermeshing gears I4 and I5 interposed between said inlet and said outlet. Intermeshing gears l4 and I5 include oppositely extending gear journals Ha, Mb, l5a and l5b. Pressure loadable and unloadable end bearing and pumping seal defining bushings indicated generally at S normally engage one side face of gears I4 and I5 in liquid pumping seal relation.

The bushing s has the rear face thereof spaced from the adjacent housing wall and is arranged to receive liquid pressure generated by the gears in contact therewith for the purpose of .pressure loading the inner face thereof in pumping s al relation with the adjacent gear side face. For anv more detailed understanding of this aspect of the case that may be desired, attention is directed. to earlier Roth and Lauck Patent No. 2,420,622, May 13, 1947. Essentially a. passage I6 extends along the bushing from adjacent the outlet area of the gear teeth to the back of the bushings while the corresponding passage adjacent the inlet area of the gear teeth is closed by a plug I1. I

A second auxiliary or energizing pump or pressure generator P2 is also contained in housing II. This second pump in combination and mode of operation forms the subject matter to which this invention is particularly directed.

Essentially, the purpose of this auxiliary or energizing pump P2 is to maintain a predetermined value of pressure acting on a motor or accumulator to thus assure the dependable operation of the pilot control valve assembly, as well as being effective to make up any small losses due to leakage (as will appear).

A pilot control valve assembly C functions to maintain the loading pressure on bushing S and hence the delivery of pressure liquid by pump PI up to a selected value of delivery pressure whereupon pilot control valve C becomes effective to relieve the loading pressure acting on bushing 8 and hence causes the discontinuance of further pressure delivery by primary pump P-i, auxiliary or energizing pump 3-! continuing to operate for the purpose of maintaining the necessary pressure for the purpose of maintaining pilot control valve C in operated condition.

\ Energizing pump P-2 comprises the formation or provision of a reduced circular cross section portion ilc at the outer portion of journal ila oi gear ll. This reduced portion has an axis olfset from the principal axis of Journal a and is eilective when Journal a is turned to reciprocate a single piston it. A connecting means it is eflfective to maintain the inner terminal'of piston il in driven cooperation with reference 7 to an eccentric 2| carried by reduced portion llc. Connecting means It is preferably in the form of a washer-like radially extending portion Na and an inturned yoke or fork portion lib embracingly received about a reduced neck Ila of piston i8 effective to confine the inner terminal ilb of piston it in driving relation to its eccentric roller 20. Connecting means I. is pref erably confined on the terminal of reduced member He by means of a snap ring llc.

Cylinder 2| for the reception of piston II is preferably in the form of an insertable sleeve Ila threadably mounted in a complementary housing bore. Sleeve Ila is formed with a radial inlet port 2ib and a radial flange Ilc cooperating with a, complementary shoulder within the housing for defining the position of the sleeve.

Check valve V-l isa one-way check valve and may be in the form of an inverted tubular member 22 having one end closed and forming the valve proper cooperating with the outer open terminal of sleeve 2i. Coll compression spring 22a is eilective to urge valve 22 in the closing direction. Closure member 23 is formed with a, complementary bore 230 for guiding reception of valve 22. Inlet passage 24 places inlet port lib in communication with the inlet line I! leading from a source of liquid while outlet passage 25 places pump P-2 in communication with outlet line I3 beyond one-way check valve V! and in communication with the pressure consumer which may be either a pressure accumulator or a ram typemotor such as indicated at M.

Pilot control valve C comprises valve V-4 which is preferably of the conical or disc type having a stem 26 connected with a, piston 21 having a cross sectionalarea corresponding to that of the valve seat engaged by valve V-J thus completely balancing valve V-t against any influence from the bushing loading pressure communicated there'through conduit 29. The outer terminal of piston 21 is placed in communication with the delivery pressure from pump P-i and P-2 through conduit 25. The cross sectional area of piston 11 and the compression strength of spring 30 are so chosen that valve v-s is opened upon the occurrence of a delivery pressure of a selected maximum value, to thus cause bushings S to move out of pumping seal engagement with the gear side faces and cause pump Pi to discontinue further delivery. 'A valve indicated generally at V# may be employed to either return the flow from motor M to the source of pressure or, alernatively, valve V--4 may be arranged to reverse the connection of fluid pressure to motor M in order to produce a power return of the motor in a well known manner.

It will thus appear that the present invention provides an eifective form and arrangement of auxiliary energizing pump in combination, capable of supplying a very, small fraction oi the volumetric displacement of the primary pump.

For the purpose of providing a suitable maximum pressure relief valve V! a one-way ball valve Ii communicates with a complementary port in the outer terminal of the bore receiving piston 21 and is urged in the closing direction by a coil spring flu.

While,the present invention has been disclosed in connection with a specific embodiment thereof it will be understood that this is by way of example rather than by way of limitation and that the invention is to be defined by the appended claims which should be given a scope commensuratewith the prior art.

- What is claimed is:

1. In a high pressure liquid pump arrangement of the type includinga first pump comprising a pair of intermeshing gears and a pressure loadable bearing and pumping seal-defining means associated therewith, conduit defining means for applying a part of the output pressure of said pump to pressure load said bearing and pumping seal defining means, and control means efi'ective to relieve the loading pressure on said seal defining means upon the occurrence of a selected value of output pressure, the combination therewith of a second energizing pump comprising a single reciprocable piston having a displacement only a small fraction of the displacement of said first pump, and means rendering the output from said second pump effective to maintain said control valve means operated to continue relieving said loading pressure following the unloading of said first pump.

2. In a high pressure liquid pump assembly of the pressure loadable and unloadable type including, a housing having an inlet thereto and an outlet therefrom; a first pump in said housing comprising a pair of intermeshing gears having axially oppositely extending journals, pressure loadable and unloadable end bearing and pumping seal defining bushing means, means delivering pressure liquid generated by said gears to said bushings for holding the same in pumping seal relation with said gears; a second auxiliary pump in said housing having a displacement that is only a small fraction of the displacement of said first pump and effective to deliver a relatively small volume of liquid to said outlet, said second pump comprising one of said gear journals being formed with a reduced circular cross section portion forming a shaft having an axis of!- set from the principal axis of the corresponding journal, a single piston, means cooperating between said reduced portion and said piston for eilecting reciprocation of said piston upon the rotation of said gear journal; a first one-way check valve between the discharge side of said gears and the discharge from said piston whereby to prevent reverse fiow from said piston to said gears; a second one-way check valve, pilot control valve means exclusively responsive to the pressure delivered beyond said check valve efiective upon the occurrence of a predetermined value of said pressure to cause the relief of the loading pressure acting on said bushing and hence the unloading of said gear pump. the continued delivery of pressure fluid by said auxiliary piston pump being efiective to maintain said pilot valve in open position and to make up any small losses due to leakage.

3. In an arrangement as defined inclaim- 2,

said auxiliary piston motor further comprising a radial bore in said housing, an externally threaded sleeve having a radial flange-like protuberant portion engaging a counterbore in said housing when said sleeve is threadably inserted cooperating with the outer terminal thereof; and

means for causing said piston to be retracted with the return rotation of said reduced journal portion comprising an anti-friction roller embracing said reduced journal portion, a sheet metal retainer clip formed with a first opening therein received in embracing relation about the outer terminal of the reduced'shait portion and an inwardly turned yoke-like portion embracingly engaging a reduced portion of said piston whereby the piston is made to follow the said roller in the retracting direction of movement thereof. I

4. In a liquid pressure loadable and unloadable pump assembly including a pair of intermeshing liquid displacing gears having axially oppositely extending journals, pressure loadable and unloadable bushings eflective to seal the gear side faces; one of said journals being formed with a reduced eccentrically positioned shaft portion, an anti-friction roller mounted for rotationon a direction parallel to saidre duced shaft and engaging said piston means for causing the same to retract said piston bodily as said reduced shaft portion is' turned; .a one-way check valve disposed between the outlet from said gears and the outlet from said piston to prevent reverse flow from said, piston to said gears; a pilot-control valve eifective upon the delivery of a pressure of predetermined value beyond said check valve for relieving said loading pressure on said bushings, said piston continuing to deliver pressure liquid efiective to maintain said pilot valve in operation following said unloading of said gear p m 5. In a pressure loadable pump of the type including a pair of intermeshing gears and pressure loadable bushings adapted to engage one side of said gears in pumping seal relation, conduit defining means for applying a part of the output pressure of said pump to pressure load said bushings, control valve means for relieving the loading said reduced shaft portion, a cylinder containing a piston having means adapted to be engaged by said roller for moving the same radially outwardly, retracting means for said piston for moving the said piston radially inwardly including a sheet-like member having a first opening therein embracing said reduced shaft portion and a pressure on said bushings upon the occurrence of a selected maximum value of output pressure of said pump, a single reciprocable piston type pump associated with said pressure loadable pump, and means for applying the output of said piston type pump to said control valve to maintain said control valve in open position to con-' tinue relieving oading pressure'following the unloading of sai bushings.

- JOHN A. LAUCK.

REFERENCES CITED UNITED'STATES PATENTS Number Name Date 1,532,326 Lent et al. Apr. 7, 1925 40 1,723,493 Schotthoefer Aug. 6, 1929 second in-turned portion extending generally in Roth et a1 May 13,1947 

